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Cu–15Ni–8Sn alloy is the best choice to replace beryllium bronze alloy. This alloy has unparalleled application value in aerospace, ocean engineering, electronic information, equipment manufacturing, and other fields. However, the application of Cu–15Ni–8Sn alloy is challenged and limited because of a series of problems in its preparation and processing, such as easy segregation, difficult deformation, and discontinuous precipitation. It is an effective way to improve the comprehensive properties of Cu–15Ni–8Sn alloy using alloying design and process optimization to control the as-cast, deformed, and heat-treated microstructures. At present, it is a hot spot for scholars to study. In this paper, the grade generation, system evolution, and preparation technology development of Cu–15Ni–8Sn alloy are comprehensively reviewed. The phase transformation sequence of the Cu–15Ni–8Sn alloy is discussed. The influence of the type, amount, and existing form of alloying elements on the strength of Cu–15Ni–8Sn alloy and its mechanism are systematically summarized. Furthermore, the latest research progress on the effects of solid solution, cold deformation, and aging on the phase structure transformation and mechanical properties of Cu–15Ni–8Sn alloy is summarized. Finally, the future development trend of the Cu–15Ni–8Sn alloy is projected. The research results of this paper can provide a reference for the control of the microstructure and properties of high-performance Cu–15Ni–8Sn alloys used in key fields, as well as the optimization of the preparation process and alloy composition. [ABSTRACT FROM AUTHOR]

During the power operation of the primary loop of a water cooled–water moderated energy reactor (WWER), the water chemistry evolves from a high-boron high-potassium composition to significantly lower concentrations of both constituents at the end of a campaign, and the Li concentration reaches ca. 0.7–0.9 ppm. In the present paper, the effect of primary water chemistry evolution during operation on the corrosion rate and conduction mechanism of oxides on Alloy 690 is studied by in situ impedance spectroscopy at 300 °C/9 MPa during 1-week exposures in an autoclave connected to a re-circulation loop. At the end of exposure, the samples were anodically polarized at potentials −0.8 to −0.1 V vs. SHE to evaluate the stability of the passive oxide. Simultaneously exposed samples of Alloy 690 were subsequently analyzed by XPS to estimate the thickness and in-depth composition of oxides. Impedance data were quantitatively interpreted using the mixed-conduction model (MCM) for oxide films. The effect of water chemistry evolution on the corrosion rate and conduction mechanism in the oxide on Alloy 690 in a primary coolant is discussed based on the obtained parameters. [ABSTRACT FROM AUTHOR]

Retrogression and re-aging (RRA) treatment has been proven to effectively overcome the trade-off between strength and corrosion resistance. Current research focuses on the heating rate, temperature, and holding time of retrogression treatment while ignoring the retrogression cooling ways. In this paper, the effects of RRA treatment with different retrogression cooling ways on the microstructure and properties of newly developed T'/η' strengthened Al-Zn-Mg-Cu alloys were investigated by performing tests on mechanical properties, intergranular corrosion (IGC) resistance, and electrochemical corrosion behavior. The results show that the mechanical properties of samples subject to RRA treatment with water-quenching retrogression (ultimate tensile strength, yield strength, and elongation of 419.2 MPa, 370.2 MPa, and 15.9, respectively) are better than those of air-cooled and furnace-cooled samples. The corrosion resistance of water-quenching (IGC depth of 162.2 μm, corrosion current density of 0.833 × 10−5 A/cm2) and furnace-cooled samples (IGC depth of 123.7 μm, corrosion current density of 0.712 × 10−5 A/cm2) is better than that of air-cooled samples. Microstructure characterization reveals that the effect of the retrogression cooling rate on mechanical properties is related to the size of T'/η' precipitates with grains as well as the proportion of T' and η', while the difference in corrosion resistance depends on the continuity of grain boundary precipitates (GBPs). With mechanical properties, corrosion resistance, and time cost taken into consideration, it is appropriate to select water quenching for retrogression. These findings offer valuable insights for further design to achieve superior performance in various applications. [ABSTRACT FROM AUTHOR]

The nanoscale Cu-rich precipitates (CRPs) are one of the most critical microstructural features responsible for degrading the mechanical properties of reactor pressure vessel (RPV) steels. The prospect of the rapid regeneration of the service performance of degraded materials through electropulsing is attractive, and electropulsing has been proven to have the application potential to eliminate the CRPs and recover the mechanical properties of RPV materials. However, few studies have investigated the secondary service issue of electropulsing. This paper provides experimental findings from microstructural investigations and property evaluations of a FeCu RPV model alloy subjected to re-aging following recovery electropulsing and annealing treatments. The evolution behavior of CRPs and the changes in the hardness of the alloy during the re-aging process after electropulsing treatment were consistent with the initial aging process, while the re-aging process of the annealing treatment group was quite different from the initial aging. The difference between the electropulsing and annealing treatment groups was that the annealing treatment failed to eliminate the precipitates completely, leaving behind some large precipitates. This work demonstrates the potential application of EPT in this field. [ABSTRACT FROM AUTHOR]

In the field of aerospace and advanced equipment manufacturing, accurate response analysis has been paid more attention, requiring a more comprehensive study of the variation of mechanical parameters with the service environment. The damping variation characteristics of 304 aluminum alloy, Sa564 high-strength alloy, GW63K magnesium alloy, and Q235 steel were investigated in this paper, which plays a significant role in the dynamic responses of structures. Variable damping ratios were revealed by the damping tests based on a dynamic mechanical analysis (DMA). The numerical method of temperature/frequency-dependent damping parameters in stochastic dynamics was focused on. With a large variation in the damping ratio, a numerical constitutive relation for temperature-dependent damping was proposed, and an efficient stochastic dynamics method was derived to analyze the responses of structures based on the pseudo excitation method (PEM) and variable damping theory. The computational accuracy and validity of the proposed method are confirmed during the vibration tests and numerical analysis. Based on the comparison results of the two damping models and the experiments on GW63K alloy, we proved that the proposed method is more accurate to the real response of the actual engineering structure. The differences in dynamic responses between the constant damping and experiments are significant, and more attention should be paid to the numerical method of stochastic dynamic response of variable damping materials in the aviation and aerospace fields and high-temperature environments. [ABSTRACT FROM AUTHOR]

This paper studies the plastic behavior of the ZK61M magnesium alloy through a combination method of experiments and theoretical models. Based on a dog-bone specimen under different loading directions, mechanical tests under uniaxial tension were carried out, and the hardening behavior was characterized by the Swift–Voce hardening law. The von Mises yield function and the pressure-coupled Drucker yield function were used to predict the load–displacement curves of the ZK61M magnesium alloy under various conditions, respectively, where the material parameters were calibrated by using inverse engineering. The experimental results show that the hardening behavior of the ZK61M magnesium alloy has obvious anisotropy, but the effect of the stress state is more important on the strain hardening behavior of the alloy. Compared with the von Mises yield function, the pressure-coupled Drucker yield function is more accurate when characterizing the plastic behavior and strain hardening in different stress states of shear, uniaxial tension, and plane strain tension for the ZK61M alloy. [ABSTRACT FROM AUTHOR]

Corrosion inhibitors represent one of the most commonly used methods for significantly reducing the corrosion rate of metals and alloys. Adsorption inhibitors have a wide range of applications in cooling water systems, deicing solutions for aircrafts, airports and ways, etching and degreasing solutions, oil pipelines, paints and coatings and metal processing solutions. Adsorption corrosion inhibitors of metals and alloys are generally organic compounds that contain structures with heteroatoms (N, P, S, As, O) in their molecules, having lone pair electrons or π electrons in aromatic rings or multiple bonds. They enable relatively strong interactions between the metal atoms and organic molecules, resulting in a protective layer of organic molecules adsorbed at the metal–corrosive solution interface. Most molecules of active substances from drugs contain similar structures, which is why many drugs have been already tested as corrosion inhibitors. One of the major disadvantages of using drugs for this purpose is their particularly high price. To overcome this impediment, the possibility of using expired drugs as corrosion inhibitors has been investigated since 2009. The present paper is an exhaustive compilation of the scientific published papers devoted to the use of expired drugs as corrosion inhibitors in various aggressive solutions. The inhibitory efficiencies of expired drugs are presented as a function of the studied metal or alloy and the nature of the aggressive solution, as well as the concentration of the inhibitor in such a solution. Research has especially been focused on mild and carbon steel and less on stainless steel, as well as on some metals such as copper, zinc, nickel, tin and aluminum and its alloys. The experimental methods used to assess the inhibitory efficiencies of expired drugs are briefly discussed. Also, the available information on the stability of the active substances in the drugs is presented, although most authors were not concerned with this aspect. Finally, several actions are revealed that must be undertaken by researchers so that the results obtained in the study of the anticorrosive action of expired drugs can be applied at the industrial level and not remain only an academic concern. [ABSTRACT FROM AUTHOR]

Additive manufacturing (AM) has experienced exponential growth over the past two decades and now stands on the cusp of a transformative paradigm shift into the realm of multi-functional component manufacturing, known as multi-material AM (MMAM). While progress in MMAM has been more gradual compared to single-material AM, significant strides have been made in exploring the scientific and technological possibilities of this emerging field. Researchers have conducted feasibility studies and investigated various processes for multi-material deposition, encompassing polymeric, metallic, and bio-materials. To facilitate further advancements, this review paper addresses the pressing need for a consolidated document on MMAM that can serve as a comprehensive guide to the state of the art. Previous reviews have tended to focus on specific processes or materials, overlooking the overall picture of MMAM. Thus, this pioneering review endeavors to synthesize the collective knowledge and provide a holistic understanding of the multiplicity of materials and multiscale processes employed in MMAM. The review commences with an analysis of the implications of multiplicity, delving into its advantages, applications, challenges, and issues. Subsequently, it offers a detailed examination of MMAM with respect to processes, materials, capabilities, scales, and structural aspects. Seven standard AM processes and hybrid AM processes are thoroughly scrutinized in the context of their adaptation for MMAM, accompanied by specific examples, merits, and demerits. The scope of the review encompasses material combinations in polymers, composites, metals-ceramics, metal alloys, and biomaterials. Furthermore, it explores MMAM's capabilities in fabricating bi-metallic structures and functionally/compositionally graded materials, providing insights into various scale and structural aspects. The review culminates by outlining future research directions in MMAM and offering an overall outlook on the vast potential of multiplicity in this field. By presenting a comprehensive and integrated perspective, this paper aims to catalyze further breakthroughs in MMAM, thus propelling the next generation of multi-functional component manufacturing to new heights by capitalizing on the unprecedented possibilities of MMAM. [ABSTRACT FROM AUTHOR]

The structure of metallic materials has a significant impact on their properties. One of the most popular methods to form the properties of metal alloys is heat treatment, which uses thermally activated transformations that take place in metals to achieve the required mechanical or physicochemical properties. The phase transformation in steel results from the fact that one state becomes less durable than the other due to a change in conditions, for example, temperature. Phase transformations are an extensive field of research that is developing very dynamically both in the sphere of experimental and model research. The objective of this paper is the development of a 3D heat flow model to model heat transfer during diffusional phase transformations in carbon steels. This model considers the two main factors that influence the transformation: the temperature and the enthalpy of transformation. The proposed model is based on the lattice Boltzmann method (LBM) and uses CUDA parallel computations. The developed heat flow model is directly related to the microstructure evolution model, which is based on frontal cellular automata (FCA). This paper briefly presents information on the FCA, LBM, CUDA, and diffusional phase transformation in carbon steels. The structures of the 3D model of heat flow and their connection with the microstructure evolution model as well as the algorithm for simulation of heat transfer with consideration of the enthalpy of transformation are shown. Examples of simulation results of the growth of the new phase that are determined by the overheating/overcooling and different model parameters in the selected planes of the 3D calculation domain are also presented. [ABSTRACT FROM AUTHOR]

TiAl alloys have excellent high-temperature performance and are potentially used in the aerospace industry. By controlling the lamellar orientation through directional solidification (DS) technology, the plasticity and strength of TiAl alloy at room temperature and high temperatures can be effectively improved. However, various difficulties lie in ensuring the lamellar orientation is parallel to the growth direction. This paper reviews two fundamental thoughts for lamellar orientation control: using seed crystals and controlling the solidification path. Multiple specific methods and their progress are introduced, including α seed crystal method, the self-seeding method, the double DS self-seeding method, the quasi-seeding method, the pure metal seeding method, and controlling solidification parameters. The advantages and disadvantages of different methods are analyzed. This paper also introduces novel ways of controlling the lamellar orientation and discusses future development. [ABSTRACT FROM AUTHOR]

Ti(C,N)-based cermet is a kind of composite material composed of a metal binder phase and a Ti(C,N)-hard phase, which is widely used in the fields of cutting machining and wear-resistant parts due to its high hardness, good toughness, wear resistance, and chemical stability. In recent years, the research on the replacement of traditional Ni, Co, and Fe binder phases by novel binder phases such as intermetallic compounds and high-entropy alloys has made remarkable progress, which significantly improves the mechanical properties, wear resistance, corrosion resistance, and high-temperature oxidation resistance of Ti(C,N)-based cermets. This paper reviews the latest research results, summarizes the mechanism of the new binder to improve the performance of metal–ceramics, and looks forward to the future research directions. [ABSTRACT FROM AUTHOR]

This paper presents a study of the total cutting force used and selected parameters of the geometric structure of the surface (e.g., Sa, Sz) during the end milling process of NiTi alloy. The input parameters included are cutting speed (vc), feed per tooth (fz), and radial depth of cut (ae). A Box–Behnken experimental design was employed to conduct the research. The obtained experimental results were utilized within the framework of a response surface methodology (RSM) to develop mathematical and statistical models capable of predicting cutting force components and selected 3D surface parameters. These models provide valuable insights into the relationships between the cutting parameters and the output variables, facilitating the optimization of the NiTi alloy milling process. The findings of this study contribute to a better understanding of the behavior of NiTi alloy during the milling process and offer information for process optimization. By employing a Box–Behnken experimental design, it was possible to investigate the effects of different parameter combinations on the components of total cutting force and selected 3D surface parameters according to ISO 25178, thus aiding in the identification of optimal milling conditions to achieve desired outcomes in the machining of NiTi alloy. [ABSTRACT FROM AUTHOR]

Al–Si–Mg alloys are most commonly used to produce parts by laser powder bed fusion for several industrial applications. A lot of papers have already focused on the effects induced by conventional heat treatments on the microstructure and mechanical properties of AlSi10Mg alloys, rather than on AlSi7Mg. Nobody has investigated thermal stability during long-term direct and artificial aging heat treatments of AlSi7Mg. This study investigates the changes in mechanical properties induced by long-term exposure (512 h) at 150 and 175 °C (the operating temperature of AlSi7Mg) after (i) the laser powder bed fusion process performed on a pre-heated build platform (150 °C), and (ii) heat treatments to the solution at 505 °C per 0.5 and 4 h. Thermal stability was evaluated through both Vickers microhardness measurements to obtain the aging profiles, and tensile tests to evaluate the mechanical properties in specific conditions. An optical microscope was used to investigate the microstructure. It was found that aging at 175 °C confers the same effects induced by a secondary aging heat treatment on as-built samples and, simultaneously, the worst effects on the solution heat treated AlSi7Mg alloy after long-term exposure. The AlSi7Mg DA at both 150 °C and 175 °C showed the same Vickers microhardness (~95 HV0.5), UTS (~300 MPa), and YS (~200 MPa) values for the longest exposure times because the fine and cellular α-Al matrix confers higher stiffness and strength despite the over-aged conditions. On the other hand, the coarsening effects that affected the precipitates during aging at 175 °C, as well as the formation of the precipitate-free zones along the grain boundaries, justified the highest detrimental effects induced on the SHTed samples. [ABSTRACT FROM AUTHOR]

Tin determination allows for the monitoring of pollution and assessment of the impact of human activities on the environment. The determination of tin in the environment is crucial for the protection of human health and ecosystems, and for maintaining sustainability. Tin can be released into the environment from various sources, such as industry, transportation, and electronic waste. The concentration of tin in the environment can be determined by different analytical methods, depending on the form of tin present and the purpose of the analysis. The choice of an appropriate method depends on the type of sample, concentration levels, and the available instrumentation. In this paper, we have carried out a literature review of electrochemical methods for the determination of tin. Electrochemical methods of analysis such as polarography, voltammetry, and potentiometry can be used for the determination of tin in various environmental samples, as well as in metal alloys. The detection limits and linearity ranges obtained for the determination of tin by different electrochemical techniques are collected and presented. The influence of the choice of base electrolyte and working electrode on signals is also presented. Practical applications of the developed tin determination methods in analyzing real samples are also summarized. [ABSTRACT FROM AUTHOR]

Sodium–potassium (NaK) liquid alloy is a promising candidate for use as an anode material in sodium batteries because of its fluidity, which effectively suppresses the growth of sodium or potassium dendrites. However, the poor wettability of NaK alloy on conventional metal substrates is unfavorable for cell fabrication due to its strong surface tension. In this paper, low-density and low-cost fluorinated aluminum foam is used as a substrate support material for NaK liquid alloy. By combining low-surface-tension NaKC with fluorinated aluminum foam, we obtain a uniformly distributed and structurally stable electrode material. The composite electrode has a cycling stability of more than 3000 h in a symmetrical cell. Furthermore, when coupled with a sulfurized polyacrylonitrile cathode in carbonate electrolyte, it maintains excellent stability even after 800 cycles, with 72% of capacity retention. [ABSTRACT FROM AUTHOR]

In the last years, additive manufacturing technologies have been developed, especially direct metal laser sintering, and used in the dental and medical implant domains. Cardiovascular stents have evolved from bioinert, bare metal cages to biomimetic devices that promote tissue regeneration or healing. In this paper, comparisons concerning mechanical properties between Co–Cr alloy and cast 304L stainless steel were realized using FEM analysis, necessary for manufacturing cardiovascular stents by DMLS technology using Co–Cr alloy. The purpose of this paper consists of the evaluation of the contact angle at the interface of the Co–Cr alloy manufactured by DMLS, respectively, cast stainless steel 304L, and thin film deposition realized by the e-gun method (Ta2O5 and ZnO). Scanning electronic microscopy SEM and EDX techniques were employed for morphological investigation of the sintered samples manufactured by the DMLS process. They were also used for semi-quantitative and qualitative chemical and metallographic analyses. The e-gun coating was used to obtain thin films with the nanometer order of Ta2O5 and ZnO with a protective role to improve the corrosion resistance, roughness, and antiseptic role. [ABSTRACT FROM AUTHOR]

This paper presents experimental investigations on the solid-state joint of 3 mm sheets of AlMg3 alloy with X2CrNiMo17-12-2 stainless steel. The study presents a dissimilar joint that was made in a solid state using a modified milling cutter. The study highlights the possibility of using this type of joint in a naval field. The paper presents all the steps of the joining process, from the technological parameters to the examination and numerical validation of the obtained specimens. A numerical model was defined in Abaqus, considering a Static analysis, and the results demonstrated a good similarity with a small discrepancy observed in the elastic range of the specimen behaviour. In the conclusions, this study will provide some recommendations for the optimisation of this joint and proposals for future studies; the idea for this study started from the dissimilar joints used in the naval field. The article also briefly presents some dissimilar joints made on the same milling machine and in the same laboratory. [ABSTRACT FROM AUTHOR]

Additive manufacturing (AM) technologies have gained considerable attention in recent years as an innovative method to produce high entropy alloy (HEA) components. The unique and excellent mechanical and environmental properties of HEAs can be used in various demanding applications, such as the aerospace and automotive industries. This review paper aims to inspect the status and prospects of research and development related to the production of HEAs by AM technologies. Several AM processes can be used to fabricate HEA components, mainly powder bed fusion (PBF), direct energy deposition (DED), material extrusion (ME), and binder jetting (BJ). PBF technologies, such as selective laser melting (SLM) and electron beam melting (EBM), have been widely used to produce HEA components with good dimensional accuracy and surface finish. DED techniques, such as blown powder deposition (BPD) and wire arc AM (WAAM), that have high deposition rates can be used to produce large, custom-made parts with relatively reduced surface finish quality. BJ and ME techniques can be used to produce green bodies that require subsequent sintering to obtain adequate density. The use of AM to produce HEA components provides the ability to make complex shapes and create composite materials with reinforced particles. However, the microstructure and mechanical properties of AM-produced HEAs can be significantly affected by the processing parameters and post-processing heat treatment, but overall, AM technology appears to be a promising approach for producing advanced HEA components with unique properties. This paper reviews the various technologies and associated aspects of AM for HEAs. The concluding remarks highlight the critical effect of the printing parameters in relation to the complex synthesis mechanism of HEA elements that is required to obtain adequate properties. In addition, the importance of using feedstock material in the form of mix elemental powder or wires rather than pre-alloyed substance is also emphasized in order that HEA components can be produced by AM processes at an affordable cost. [ABSTRACT FROM AUTHOR]

For tailoring the mechanical and magnetic properties of dual-phase high-entropy alloys (HEAs), it is crucial to understand the effect of each phase on the overall properties. In this paper, the effects of individual FCC and BCC phases on the mechanical and magnetic properties of the FeCoNi(CuAl)0.8 HEA are investigated by nanoindentation and first-principles calculations. The nano-hardness of the BCC phase is 8.73 GPa, which is nearly double the 4.60 GPa of the FCC phase, which ascribes to spherical nanoprecipitates that are only observed in the BCC phase leading to precipitation hardening. First-principles calculations on the electronic structure show that calculated saturation magnetization (Ms) of the BCC phase is 0.81 T, higher than 0.77 T of the FCC phase. An approximate yield strength and Ms can be estimated by summing the volume-fraction-weighted contributions from each phase, and are in good agreement with experimental values. It indicates that the overall mechanical and magnetic properties of the dual-phase HEAs can be tailored by tuning the volume fraction of the individual phase. Our findings are helpful to design prospective dual-phase HEAs with both good mechanical properties and soft magnetic performance by adjusting the content of each phase. [ABSTRACT FROM AUTHOR]

The effect of heat treatment on the microstructure and tensile properties of an as-cast Al0.6CoCrFeNi high-entropy alloy (HEA) was investigated in this paper. The results show that the as-cast Al0.6CoCrFeNi HEA presents a typical FCC dendrite morphology with the interdendritic region consisting of BCC/B2 structure and heat treatment can strongly affect the microstructure and mechanical properties of HEA. Microstructure analysis revealed the precipitation of a nano-sized L12 phase in the FCC dendrite and the formation of the FCC and σ phases in the interdendritic region after annealing at 700 °C. The coarse B2 phase was directly precipitated from the FCC dendrite in the 900 °C-annealed sample, with the coexistence of the B2, FCC, and σ phases in the interdendritic region. Then, the interdendritic region converted to a B2 and FCC dual-phase structure caused by the re-decomposition of the σ phase after annealing at 1100 °C. The tensile test results show that the 700 °C-annealed HEA presents the most significant strengthening effect, with increments of corresponding yield strength being about 107%, which can be attributed to the numerous nano-sized L12 precipitates in the FCC dendrite. The mechanical properties of 1100 °C-annealed alloy revert to a level close to that of the as-cast alloy, which can be attributed to the coarsening mechanism of B2 precipitates and the formation of a soft FCC phase in the interdendritic region. The observed variation in mechanical properties during heat treatment follows the traditional trade-off relationship between strength and plasticity. [ABSTRACT FROM AUTHOR]

The aim of this paper was to optimise the manufacturing parameters of a new maraging steel alloy with 8% Cr, reduced Ni content (7%), and no Co or Mo. This alloy was developed by ArcelorMittal and its trade name is LeanSi. The alloy was produced using the selective laser melting (SLM) process. In the as-built state, the microstructure of the alloy was fully martensitic. The optimisation of the manufacturing parameters was determined via a multivariate factorial design of experiments including 12 experiments and three factors. The factors (i.e., the fabrication parameters) analysed were laser power, scanning speed, and hatch distance. The objective was to eliminate porosity and maximise density. It was concluded that, to achieve this, the laser power should be set at 250 W, the scanning speed at 1000 mm/s, and the hatch distance at 80 microns. The porosity obtained under these manufacturing parameters was 0.06 ± 0.03% with a confidence level of 95%. If these manufacturing parameters were modified, the material exhibited a defective interlayer bond with the formation of "balling" and high porosity. The tensile specimens tested in the as-built state showed plastic deformation. However, all the aged specimens showed brittle fracture behaviour, evidenced by the presence of very small micro-cavities (where the fracture energy consumed was very small) and small cleavage planes. The specimens produced with the manufacturing parameters at their optimum levels and aged at 480 °C for 2 h achieved tensile strength values that averaged 1430 MPa. The porosity of these specimens was reduced by more than 85%. Reverse austenite was detected at ageing temperatures of 540 °C upwards. [ABSTRACT FROM AUTHOR]

The effects of Mn addition on the room temperature tensile strength and deformation mechanisms of as-cast Mg-8Al-1Nd-1.5Gd-xMn alloys (x = 0, 0.3, 0.5, 1.0 wt.%) are investigated in this paper. The results indicate that the addition of Mn contributes to the precipitation of Al-Mn-RE intermetallics and the refinement of α-Mg matrices, thereby improving the tensile strength of the 1.0 Mn alloy at 190 MPa. The fracture mechanism of Mn-containing alloys transforms from a cleavage fracture to a ductile fracture as the Mn content increases from 0.3 to 1.0 wt.%. The presence of intermetallic particles in the dimples confirms the hindrance effect of Al10Mn2 (Nd,Gd) on dislocation slips. The novel technology of in-grain misorientation axes (IGMAs) is used to identify activated slip modes and deformation twins. It can be concluded that the activated pyramidal slip during tensile deformation significantly promotes the ductility of the 1.0 Mn alloy with an elongation rate of 9.8%. It is worth noting that reducing the coarse 10 1 ¯ 2 tensile twins and enhancing the proportion of 10 1 ¯ 1 compressive twins and 10 1 ¯ 1 - 10 1 ¯ 2 double twins contributes to maintaining the continuous plastic deformation of Mg alloy. [ABSTRACT FROM AUTHOR]

Due to its excellent physical properties, γ-TiAl alloy has been widely used in thin-walled components of aerospace engines. However, issues such as low thermal conductivity, poor machinability, and high cutting temperatures often result in difficulties in ensuring the geometric accuracy and surface integrity of the parts. This paper focuses on the study of the thermal deformation behavior of γ-TiAl alloy within a range of higher temperatures and strain rates. Firstly, by conducting quasi-static tests and Hopkinson bar tests on γ-TiAl alloy, the true stress–strain curves of γ-TiAl alloy are obtained within a temperature range of 20~500 °C and a strain rate range of 3000~11,000/s. Based on the Johnson–Cook model, the true stress–strain curves are fitted and analyzed with consideration of the coupling effect of strain rate, temperature, and strain. The strain rate hardening coefficient C and thermal softening exponent m are polynomialized, improving the Johnson–Cook constitutive model of γ-TiAl alloy. The improved model shows significant improvements in the correlation coefficient and absolute errors between the predicted values and experimental values, providing a better reflection of the thermal deformation behavior of γ-TiAl alloy within a range of higher temperatures and strain rates. [ABSTRACT FROM AUTHOR]

Hybrid metal matrix composites (HMMCs) are a special type of material, possessing combined properties that belong to alloys and metals according to market demands. Therefore, they are used in different areas of industry and the properties of this type of material are useful in engineering applications, e.g., in aircraft engines and electrotechnical parts. The structure of the material requires a number of scientific studies to develop an appropriate processing technology. The paper presents the susceptibility of material from the HMMCs group with the EN AC-44300 (AISi12(Fe)) aluminum alloy matrix with a two-component reinforcement made of alumina particles (AP) and aluminosilicate fibers (AF) to thermal treatment with a laser beam. During this process, laser engraving of the researched material with variable beam power Pav and variable speed of the laser head vl were carried out. A metallographic analysis of the material was carried out. After laser engraving, surface structural changes of the material were determined. The properties of the surface geometric structure of processed material were also examined. Presented studies concern laser engraving on the surface of composite from the HMMC group, which was made by vacuum infiltration. Thanks to this method, it is possible both to produce shaped and precise composite castings with saturated reinforcement and to consequently minimize machining losses. Metal–ceramic composites from the HMMC group are hard-to-machine materials which create problems during machining. The aim of these studies was to develop a laser engraving technology with Al matrix composite with the addition of Al2O3 particles and aluminosilicate fibers, which constitute the reinforcement. The focus was on the selection of engraving parameters (beam power and speed of movement of the laser head). Clear examples of engraving, suitable for macro-assessment, were obtained with minimal change in the initial surface structure of the composite. [ABSTRACT FROM AUTHOR]

High-entropy alloys (HEAs) gained interest in the field of biomedical applications due to their unique effects and to the combination of the properties of the constituent elements. In addition to the required property of biocompatibility, other requirements include properties such as mechanical resistance, bioactivity, sterility, stability, cost effectiveness, etc. For this paper, a biocompatible high-entropy alloy, defined as bio-HEA by the literature, can be considered as an alternative to the market-available materials due to their superior properties. According to the calculation of the valence electron concentration, a majority of body-centered cubic (BCC) phases were expected, resulting in properties such as high strength and plasticity for the studied alloy, confirmed by the XRD analysis. The tetragonal (TVC) phase was also identified, indicating that the presence of face-centered cubic (FCC) phases in the alloyed materials resulted in high ductility. Microstructural and compositional analyses revealed refined and uniform metallic powder particles, with a homogeneous distribution of the elemental particles observed from the mapping analyses, indicating that alloying had occurred. The technological characterization of the high-entropy alloy-elaborated powder revealed the particle dimension reduction due to the welding and fracturing process that occurs during mechanical alloying, with a calculated average particle size of 45.12 µm. [ABSTRACT FROM AUTHOR]

The effect of Al and Ti additions on the microstructure and properties of CoNiFe alloys was studied in this paper. The investigations were conducted on four specially designed and produced arc furnace alloys (from 3 to 5 components, with medium to high entropy). Samples in various states were analyzed, i.e., as-cast, after homogenization, after solution heat treatment, and after solution heat treatment and aging. The obtained samples were characterized by: SEM observations, EDS, XRD, TEM analyses, and finally, hardness measurements. The solid solution strengthening coming from the addition of 5 at. pct. Al was negligible, while the effect from the 5 at. pct. of Ti addition was significant. The precipitation hardening effect related to the presence of the (CoNi)3Ti phase caused by the Ti addition is comparable with the total effect of the Al and Ti addition, which caused the precipitation of (NiCo)3AlTi. [ABSTRACT FROM AUTHOR]

This paper presents a new solution for shaping the rivet progression of a beverage end. The classic method uses three operations to press the cylindrical rivet using 0.208 mm and 0.203 mm thick sheets. The increasing demand for aluminium alloys is prompting measures to make more efficient use of this raw material. One possible solution is to produce packaging from ever thinner sheets. This requires the design of new tooling and the preparation of an appropriate technological process. A method has been developed to stamp a hexagonal-shaped rivet from 0.200 mm thick sheet metal, increasing the number of stamping operations to four. The proposed method was verified through a numerical analysis using the PAM STAMP 2022.0 software package. It was found that for appropriately shaped tools, sheet thicknesses of the stamped component could be achieved that were not less than those for the currently used technology, thus eliminating any possible break in the material structure. Suitable tools and experimental stamping tests were carried out for the developed process. In the simulations, the material Al5182_iso_Xmm was adopted from the programme database, while the experiments were performed on a laboratory press using AW-5182-H48 sheets with a thickness of 0.200 mm. The purpose of the study was to determine the validity for the proposed method of forming the rivet of the beverage end. [ABSTRACT FROM AUTHOR]

The article presents the results of mechanical testing of Ni-P/Si3N4 nanocomposite and hybrid Ni-P/Si3N4/graphite coatings deposited on AW-7075 aluminum alloy using the chemical reduction method. In terms of mechanical testing, microhardness was measured, and surface roughness and adhesion of the coatings to the aluminum substrate were determined using the "scratch test" method. The surface morphology of the deposited layers was also analyzed using light microscopy and scanning electron microscopy. Samples made of AW-7075 aluminum alloy with electroless deposited Ni-P/Si3N4 nanocomposite, Ni-P/graphite composite and hybrid Ni-P/Si3N4/graphite coatings with different content of dispersed phases were tested, and also, for comparison purposes, the Ni-P layer that constituted the matrix of the tested materials. Reinforcing phases in the form of silicon nitride nanoparticles and graphite particles were used in the layers. The purpose of the research was a thorough characterization of the coating materials used on aluminum alloys in terms of mechanical properties. Graphite is considered in this paper as it enables the reduction of the coefficient of friction through its lubricating properties. Unfortunately, graphite is difficult to use in selected layers as the only dispersion phase, because it has much lower hardness than the Ni-P coating. For this reason, a layer with a single dispersion phase in the form of graphite will be characterized by worse mechanical properties. It is necessary to add particles or nanoparticles with hardness higher than the base Ni-P coating, e.g., Si3N4, which improve the mechanical properties of the coating. The presented analyses of the results of the conducted research complement the previous studies on selected properties of nanocomposite layers with an amorphous structure and supplement the knowledge regarding their suitability for application to aluminum machine parts. [ABSTRACT FROM AUTHOR]

Metal matrix composites (MMCs) are a special class of materials carrying combined properties that belongs to alloys and metals according to market demands. Therefore, they are used in different areas of industry, and the properties of this type of material are useful in engineering applications. Machining of such composites is of great importance to finalize the fabrication process with improved part quality. However, the process implies several challenges due to the complexity of the cutting processes and random material structure. The current study aims to examine machinability characteristics. Effects of turning a metal matrix composite built of Al2O3 sinter, saturated with an EN AC-44000 AC-AlSi11 alloy, are presented in this paper. In the present study, a turning process of new metal matrix composites was carried out to determine the state-of-the-art material for various engineering applications. During the turning process, the cutting forces, a tool's wear, and surface roughness were investigated. Further, the SEM (scanning electron microscope) analysis of cutting inserts was performed. The influence of MMC structure on the machining process and surface roughness was studied. The Al2O3 reinforcements were used in different graininess. Effects of conventional turning of the metal matrix composite with Al2O3 sinter of FEPA (Federation of European Producers of Abrasives) 046 and FEPA 100 grade were compared. Results analysis of these tests showed the necessity of continuing research on turning metal matrix composites built of an AlSi alloy and Al2O3 ceramic reinforcement. The study showed the properties of MMCs that influenced machinability. In this paper, the influence of feed rate's value on surface roughness was carried out. The significant tool wear during the turning of the MMC was proved. [ABSTRACT FROM AUTHOR]

Shape memory effects coupled with superelasticity are the distinctive characteristics of shape memory alloys (SMAs), a type of metal. When these alloys are subject to thermomechanical processing, they have the inherent ability to react to stimuli, such as heat. As a result, these alloys have established their usefulness in a variety of fields and have in recent years been chosen for use in stents, sensors, actuators, and several other forms of life-saving medical equipment. When it comes to the shape memory materials, nickel–titanium (Ni-Ti) alloys are in the forefront and have been chosen for use in a spectrum of demanding applications. As shape memory alloys (SMAs) are chosen for use in critical environments, such as blood streams (arteries and veins), orthodontic applications, orthopedic implants, and high temperature surroundings, such as actuators in aircraft engines, the phenomenon of environment-induced degradation is of both interest and concern. Hence, the environment-induced degradation behavior of the shape memory alloys (SMAs) needs to be studied to find viable ways to improve their resistance to an aggressive environment. The degradation that occurs upon exposure to an aggressive environment is often referred to as corrosion. Environment-induced degradation, or corrosion, being an unavoidable factor, certain techniques can be used for the purpose of enhancing the degradation resistance of shape memory alloys (SMAs). In this paper, we present and discuss the specific role of microstructure and contribution of environment to the degradation behavior of shape memory alloys (SMAs) while concurrently providing methods to resist both the development and growth of the degradation caused by the environment. [ABSTRACT FROM AUTHOR]

In the present paper, the influence of partial substitution of Mn by Pd on structure, thermomagnetic properties, and phase transitions in the MnCoGe alloys was investigated. The studies of phase constitution revealed an occurrence of the orthorhombic TiNiSi-type and hexagonal Ni2Ti- type phases. Deep analysis of the XRD pattern supported by the Rietveld analysis allowed us to notice the changes in lattice parameters and quantity of recognized phases depending on the Pd content. An increase of palladium in alloy composition at the expense of manganese induced a rise in the Curie temperature. The values of ΔSM measured for the variation of external magnetic field ~5 T equaled 8.88, 23.99, 15.63, and 11.09 for Mn0.97Pd0.03CoGe, Mn0.95Pd0.05CoGe, Mn0.93Pd0.07CoGe, and Mn0.9Pd0.1CoGe alloy, respectively. The highest magnetic entropy change ΔSM was observed for samples with Pd content x = 0.05 induced by magnetostructural transformation. The analysis of the n vs. T curves allowed confirmation of the XRD and DSC results of an occurrence of the first-order magnetostructural transition in Mn0.95Pd0.05CoGe and Mn0.93Pd0.07CoGe alloys samples. [ABSTRACT FROM AUTHOR]

The paper presents the results of tests of rapid solidification (RS) aluminum alloys with the addition of silicon (5%, 11%, and 20%). Casting by melt-spinning on the surface of an intensively cooled copper cylinder allowed to obtain a metallic material in the form of flakes, which were then consolidated in the process of pressing and direct extrusion. The effect of refinement on structural components after rapid solidification was determined. Rapidly solidified AlSi materials are characterized by a comparable size of Si particles, regardless of the silicon content, and the shape of these particles is close to spheroidal. Not only Si particles are fragmented, but also the Al-Si-Fe phase, which also changed its shape from irregular with sharp edges to regular and spherical. The melt-spinning process resulted in a fine-grained structure compared to materials obtained by gravity-casting and extrusion. The influence of the high-temperature compression test on the mechanical properties of rapidly solidified materials was analyzed, and the results were compared with those of gravity-cast materials. An increase in strength properties was found in the case of the AlSi5 RS alloy by 20%, in the case of AlSi11RS by 25%, and in the case of the alloy containing 20% Si by as much as 86% (tensile test). On the basis of the homogeneity of the particle distribution determined by the SEM method, it was found that rapid solidification is an effective method of increasing the strength properties and improving the plastic properties of Al-Si alloys. [ABSTRACT FROM AUTHOR]

This paper presents results on the microstructure and mechanical properties of a new low-cost titanium alloy Ti-5Al-1.5Mo-1.8Fe after different forging processes. The β phase transformation temperature of this alloy was 950 °C. In this study, the forging temperatures were designed at 920 °C and 980 °C, and the deformation degree ranged from 20% to 60%, with an interval of 20%. This study investigated the impact of the equiaxed α phase and shape of the lamellar microstructure on the tensile characteristics and fracture toughness of an alloy. The research employed a microstructure analysis and static tensile testing to evaluate the effect of forging temperatures and degree of deformation on the microstructure features. The findings revealed that forging temperatures could modify the microstructure characteristics, and the degree of deformation also affected this microstructure. This study demonstrates that a bimodal structure with an equiaxed α phase can be utilized to balance high strength and high ductility, resulting in better overall mechanical properties. [ABSTRACT FROM AUTHOR]

The paper studies new materials for brake disks used in car manufacturing. The materials used in the manufacturing of the brake disc must adapt and correlate with the challenges of current society. There is a tremendous interest in the development of a material that has high strength, good heat transfer, corrosion resistance and low density, in order to withstand high-breaking forces, high heat and various adverse environment. Low-density materials improve fuel efficiency and environmental impact. Complex concentrated alloys (CCA) are metallic element mixtures with multi-principal elements, which can respond promisingly to this challenge with their variety of properties. Several compositions were studied through thermodynamic criteria calculations (entropy of mixing, enthalpy of mixing, lambda coefficient, etc.) and CALPHAD modeling, in order to determine appropriate structures. The selected compositions were obtained in an induction furnace with a protective atmosphere and then subjected to an annealing process. Alloy samples presented uniform phase distribution, a high-melting temperature (over 1000 °C), high hardness (1000–1400 HV), good corrosion resistance in 3.5 wt.% NaCl solution (under 0.2 mm/year) and a low density (under 6 g/cm3). [ABSTRACT FROM AUTHOR]

Although heat-treatable Al-Zn-Mg-Cu alloys are widely used in aerospace industries, distortion and cracks exist due to the residual stress during quenching. Understanding the flow stress behavior and numerically modeling the process is the key to predicting the residual stress. This paper investigated the flow stress behavior of the as-quenched 7050 alloy at strain rates from 0.1 s−1 to 1 s−1, temperatures between 423 K and 723 K, and cooling rates from 0.1 K/s to 10 K/s. The experimental results showed that the strain rate, cooling rate, and temperature have effects on the flow stress value, except for the cooling rates at a temperature of 423 K or 723 K. The kinetics model was used to obtain the precipitate features, i.e., precipitate size and volume fraction. Then, a physical constitutive model based on the evolution of immobile dislocation, solutes, and precipitates was developed. The predicted flow stresses showed good agreement with the experimental data. The findings of this work expand the knowledge on the as-quenched flow behavior of Al-Zn-Mg-Cu alloys, improving the prediction accuracy of residual stress by FEM. [ABSTRACT FROM AUTHOR]

In this paper, the high strength and lightweight Al–Cu–Li alloy (AA2099) is considered in as-built and preheated conditions (440 °C, 460 °C, 480 °C, 500 °C, and 520 °C). The purpose of this study is to investigate the influence of laser powder bed fusion (LPBF) in situ preheating on precipitation microstructure, mechanical and corrosive properties of LPBF-printed AA2099 alloy compared to the conventionally processed and heat-treated (T83) alloy. It is shown that precipitations evolve with increasing preheating temperatures from predominantly globular Cu-rich phases at lower temperatures (as-built, 440 °C) to more plate and rod-like precipitates (460 °C, 480 °C, 500 °C and 520 °C). Attendant increase with increasing preheating temperatures are the amount of low melting Cu-rich phases and precipitation-free zones (PFZ). Hardness of preheated LPBF samples peaks at 480 °C (93.6 HV0.1), and declines afterwards, although inferior to the T83 alloy (168.6 HV0.1). Preheated sample (500 °C) shows superior elongation (14.1%) compared to the T83 (11.3%) but falls short in tensile and yield strength properties. Potentiodynamic polarization results also show that increasing preheating temperature increases the corrosion current density (Icorr) and corrosion rate. Indicated by the lower oxide resistance (Rox), the Cu-rich phases compromise the integrity of the oxide layer. [ABSTRACT FROM AUTHOR]

Zinc (Zn)-based biodegradable materials show moderate degradation rates in comparison with other biodegradable materials (Fe and Mg). Biocompatibility and non-toxicity also make them a viable option for implant applications. Furthermore, Pure Zn has poor mechanical behavior, with a tensile strength of around 100–150 MPa and an elongation of 0.3–2%, which is far from reaching the strength required as an orthopedic implant material (tensile strength is more than 300 MPa, elongation more than 15%). Alloy and composite fabrication have proven to be excellent ways to improve the mechanical performance of Zn. Therefore, their alloys and composites have emerged as an innovative category of biodegradable materials. This paper summarizes the most important recent research results on the mechanical and biological characteristics of biodegradable Zn-based implants for orthopedic applications and the most commonly added components in Zn alloys and composites. [ABSTRACT FROM AUTHOR]

Ti6AL4V alloy is widely used in the biomedical and energy vehicle industries, among others. Ti6Al4V alloy cannot be fabricated at ambient temperatures; hence, it requires hot forming. However, this method is susceptible to crack defects. The crack defect problem of Ti6AL4V alloy in the hot-forming process cannot be ignored, so we must develop a precise hot-forming damage prediction model. In this study, three high-temperature damage models of Ti6Al4V alloy were developed, considering the temperature and strain rate. These models were derived from the normalized Cockcroft and Latham (NCL), Oyane, and Rice and Tracey (RT) damage models. The damage parameters of the models were identified using a genetic algorithm combined with finite element simulation. The force accumulation error of the Ti6AL4V alloy specimen, which was obtained from a simulated thermal tensile test and an actual test, was used as an optimization target function. Then, the damage parameters were optimized using the genetic algorithm until the target function reached the minimum value. Finally, the optimal damage model parameter was obtained. Through program development, the three high-temperature damage models established in this paper were embedded into Forge® NxT 2.1 finite element software. The simulated thermal tensile test of Ti6AL4V alloy was performed at a temperature of 800–1000 °C and a strain rate of 0.01–5 s−1. The simulated and actual fracture displacements of the tensile specimens were compared. The correlation coefficients (R) were calculated, which were 0.997, 0.951, and 0.912. Of the high-temperature damage models, the normalized Cockcroft and Latham high-temperature damage model had higher accuracy in predicting crack defects of Ti6Al4V alloy during the hot-forming process. Finally, a fracture strain graph and a high-temperature damage graph of Ti6Al4V alloy were constructed. The Ti6Al4V alloy damage evolution and thermal formability were analyzed in relation to the temperature and strain rate. [ABSTRACT FROM AUTHOR]

A precise constitutive model is the foundation and key to finite element simulation in material volume forming and the optimization of the hot working process. Hence, to build a precise constitutive model, a method based on a genetic algorithm (GA) for the inverse optimization identification of parameters is presented in this paper. The idea of this method is to continuously adjust the model parameters through GA until the objective function reaches the minimum value. In this study, hot compression experiments were performed on the Gleeble-1500D thermal simulator at temperatures ranging from 800 °C to 1000 °C and strain rates of 0.01 s−1 to 1 s−1. The Arrhenius-type (A-T) model considering strain compensation and the Johnson–Cook (JC) model considering the coupling effects of strain, temperature and strain rate were constructed, respectively, by using the regression method and the parameter inverse optimization identification method. For the purposes of comparing and verifying the reliability of the predictions of the two established constitutive models, the correlation coefficient (R), average absolute relative error (AARE), and relative error (RE) were adopted. The results show that both the optimized A-T model and the optimized JC model have high prediction accuracy. Compared to the optimized JC model, the optimized A-T model demonstrated a higher correlation coefficient, by 0.003, and a lower average absolute relative error, by 1.43%. Furthermore, the relative error distribution of the optimized A-T model was found to be more concentrated than that of the optimized JC model. These results suggest that the A-T model is more appropriate than the JC model for characterizing the high-temperature deformation behavior of Ti6Al4V alloy. [ABSTRACT FROM AUTHOR]

The most critical shortcoming of magnesium alloys from the point of view of medical devices is the high corrosion rate, which is not well-correlated with clinical needs. It is well- known that rapid degradation occurs when an implant made of Mg-based alloys is placed inside the human body. Consequently, the implant loses its mechanical properties and failure can occur even if it is not completely degraded. The corrosion products that appear after Mg-based alloy degradation, such as H2 and OH− can have an essential role in decreasing biocompatibility due to the H2 accumulation process in the tissues near the implant. In order to control the degradation process of the Mg-based alloys, different coatings could be applied. The aim of the current paper is to evaluate the effect of fluoride coatings on the corrosion behavior of magnesium alloys from the system Mg–Zn–Ca–Mn potentially used for orthopedic trauma implants. The main functional properties required for the magnesium alloys to be used as implant materials, such as surface properties and corrosion behavior, were studied before and after surface modifications by fluoride conversion, with and without preliminary sandblasting, of two magnesium alloys from the system Mg–Zn–Ca–Mn. The experimental results showed that chemical conversion treatment with hydrofluoric acid is useful as a method of increasing corrosion resistance for the experimental magnesium alloys from the Mg–Zn–Ca–Mn system. Also, high surface free energy values obtained for the alloys treated with hydrofluoric acid correlated with wettability lead to the conclusion that there is an increased chance for biological factor adsorption and cell proliferation. Chemical conversion treatment with hydrofluoric acid is useful as a method of increasing corrosion resistance for the experimental Mg–Zn–Ca–Mn alloys. [ABSTRACT FROM AUTHOR]

To meet the demand for more extensive applications of Mg alloys, a Mg-5Al-2Ca-1Mn-0.5Zn alloy without RE was prepared in this paper, and its mechanical properties were further improved by conventional hot extrusion and subsequent rotary swaging. The results show that the hardness of the alloy decreases along the radial central region after rotary swaging. The strength and hardness of the central area are lower, but the ductility is higher. The yield strength and ultimate tensile strength of the alloy in the peripheral area after rotary swaging reach 352 MPa and 386 MPa, respectively, while the elongation remains at 9.6%, exhibiting better strength–ductility synergy. The grain refinement and dislocation increase caused by rotary swaging promoted strength improvement. The activation of non-basal slips during rotary swaging is an important reason for the alloy to maintain good plasticity while improving strength. [ABSTRACT FROM AUTHOR]

In this paper, FeCrCoW alloys with different W contents (0.4, 2.1 and 3.4 at%) are designed and studied in order to overcome the existing shortcomings of resistance materials. These resistance materials have high resistivity and a low temperature coefficient of resistivity. It is observed that the addition of W has a remarkable effect on the phase structure of the alloy. In particular, when the W content is 3.4 at%, the single BCC phase of the alloy can be transformed into the BCC and FCC phase. Meanwhile, when analyzed by transmission electron microscopy, there are stacking faults and martensite in FeCrCoW alloy with W content of 3.4 at%. These features are related to excessive W content. In addition, the strength of the alloy can be improved, and the ultimate tensile strength and yield strength are both very high, which are considered as grain-boundary strengthening and solid solution strengthening, caused by the addition of W. The electrical resistivity of the FeCrCoW alloys decreases when the content of W is more than 2.1 at%. The maximum resistivity of the alloy is 170 ± 1.5 μΩ·cm. Moreover, the unique properties of the transition metal allow the alloy to have a low temperature coefficient of resistivity in the temperature range of 298~393 K. The temperature coefficient of resistivity values of the W0.4, W2.1 and W3.4 alloys are −0.0073, −0.0052 and −0.0051 ppm/K. Therefore, this work provides a vision for resistance alloys, which can achieve highly stable resistivity and high strengths in a certain temperature range. [ABSTRACT FROM AUTHOR]

High-entropy alloy (HEA) is a new type of multi-principal alloy material and the Hf-Nb-Ta-Ti-Zr HEAs have attracted more and more attention from researchers due to their high melting point, special plasticity, and excellent corrosion resistance. In this paper, in order to reduce the density of the alloy and maintain the strength of the Hf-Nb-Ta-Ti-Zr HEAs, the effects of high-density elements Hf and Ta on the properties of HEAs were explored for the first time based on molecular dynamics simulations. A low-density and high-strength Hf0.25NbTa0.25TiZr HEA suitable for laser melting deposition was designed and formed. Studies have shown that the decrease in the proportion of Ta element reduces the strength of HEA, while the decrease in Hf element increases the strength of HEA. The simultaneous decrease in the ratio of Hf and Ta elements reduces the elastic modulus and strength of HEA and leads to the coarsening of the alloy microstructure. The application of laser melting deposition (LMD) technology refines the grains and effectively solves the coarsening problem. Compared with the as-cast state, the as-deposited Hf0.25NbTa0.25TiZr HEA obtained by LMD forming has obvious grain refinement (from 300 μm to 20–80 μm). At the same time, compared with the as-cast Hf0.25NbTa0.25TiZr HEA (σs = 730 ± 23 MPa), the as-deposited Hf0.25NbTa0.25TiZr HEA has higher strength (σs = 925 ± 9 MPa), which is similar to the as-cast equiatomic ratio HfNbTaTiZr HEA (σs = 970 ± 15 MPa). [ABSTRACT FROM AUTHOR]

This paper presents simulation results of the ionization losses of incident He2+ ions with an energy of 40 keV during the passage of incident ions in the near-surface layer of alloys based on TiTaNbV with a variation of alloy components. For comparison, data on the ionization losses of incident He2+ ions in pure niobium, followed by the addition of vanadium, tantalum, and titanium to the alloy in equal stoichiometric proportions, are presented. With the use of indentation methods, the dependences of the change in the strength properties of the near-surface layer of alloys were determined. It was established that the addition of Ti to the composition of the alloy leads to an increase in resistance to crack resistance under high-dose irradiation, as well as a decrease in the degree of swelling of the near-surface layer. During tests on the thermal stability of irradiated samples, it was found that swelling and degradation of the near-surface layer of pure niobium affects the rate of oxidation and subsequent degradation, while for high-entropy alloys, an increase in the number of alloy components leads to an increase in resistance to destruction. [ABSTRACT FROM AUTHOR]

Metal injection molding (MIM) is one of the most widely used manufacturing processes worldwide as it is a cost-effective way of producing a variety of dental and orthopedic implants, surgical instruments, and other important biomedical products. Titanium (Ti) and Ti alloys are popular modern metallic materials that have revamped the biomedical sector as they have superior biocompatibility, excellent corrosion resistance, and high static and fatigue strength. This paper systematically reviews the MIM process parameters that extant studies have used to produce Ti and Ti alloy components between 2013 and 2022 for the medical industry. Moreover, the effect of sintering temperature on the mechanical properties of the MIM-processed sintered components has been reviewed and discussed. It is concluded that by appropriately selecting and implementing the processing parameters at different stages of the MIM process, defect-free Ti and Ti alloy-based biomedical components can be produced. Therefore, this present study could greatly benefit future studies that examine using MIM to develop products for biomedical applications. [ABSTRACT FROM AUTHOR]

Surface modification of metallic alloys can create hydrophilic or hydrophobic surfaces that enhance the functional performance of the material. For example, hydrophilic surfaces have improved wettability, which improves mechanical anchorage in adhesive bonding operations. This wettability is directly related to the type of texture created on the surface and the roughness obtained after the surface modification process. This paper presents the use of abrasive water jetting as an optimal technology for the surface modification of metal alloys. A correct combination of high traverse speeds at low hydraulic pressures minimises the power of the water jet and allows for the removal of small layers of material. The erosive nature of the material removal mechanism creates a high surface roughness, which increases its surface activation. In this way, the influence of texturing with and without abrasive has been evaluated, reaching combinations where the absence of abrasive particles can produce surfaces of interest. In the results obtained, the influence of the most relevant texturing parameters between hydraulic pressure, traverse speed, abrasive flow and spacing has been determined. This has allowed a relationship to be established between these variables and surface quality in terms of Sa, Sz and Sk, as well as wettability. [ABSTRACT FROM AUTHOR]

The effect of implanting 57Fe ions on the crystal structure of Nb–Zr alloys has been studied using Mössbauer spectroscopy on 57Fe nuclei and X-ray diffraction. As a result of implantation, a metastable structure was formed in the Nb–Zr alloy. The XRD data indicated a decrease in the crystal lattice parameter of niobium; that is, there was a compression of the niobium planes when implanted with iron ions. Mössbauer spectroscopy revealed three states of iron. The singlet indicated a supersaturated Nb(Fe) solid solution; the doublets characterized the diffusion migration of atomic planes and crystallization of voids. It was shown that the values of the isomer shifts in all three states did not depend on the implantation energy, which indicates the invariance of the electron density on the 57Fe nuclei in the studied samples. The resonance lines of the Mössbauer spectra were significantly broadened, which is typical for materials with low crystallinity and a metastable structure that is stable at room temperature. The paper discusses the mechanism of radiation-induced and thermal transformations in the Nb–Zr alloy, which leads to the formation of a stable well-crystallized structure. A Fe2Nb intermetallic compound and the Nb(Fe) solid solution formed in its near-surface layer, while Nb(Zr) remained in the bulk. [ABSTRACT FROM AUTHOR]

Magnesium and magnesium-based alloys are widely used in the transportation, aerospace and military industries because they are lightweight, have good specific strength, a high specific damping capacity, excellent electromagnetic shielding properties and controllable degradation. However, traditional as-cast magnesium alloys have many defects. Their mechanical and corrosion properties cause difficulties in meeting application requirements. Therefore, extrusion processes are often used to eliminate the structural defects of magnesium alloys, and to improve strength and toughness synergy as well as corrosion resistance. This paper comprehensively summarizes the characteristics of extrusion processes, elaborates on the evolution law of microstructure, discusses DRX nucleation, texture weakening and abnormal texture behavior, discusses the influence of extrusion parameters on alloy properties, and systematically analyzes the properties of extruded magnesium alloys. The strengthening mechanism is comprehensively summarized, the non-basal plane slip, texture weakening and randomization laws are comprehensively summarized, and the future research direction of high-performance extruded magnesium alloys is prospected. [ABSTRACT FROM AUTHOR]

The effects of Al addition on the microstructure and mechanical properties of Mg-Zn-Sn-Mn-Ca alloys are studied in this paper. It was found that the Mg-6Sn-4Zn-1Mn-0.2Ca-xAl (ZTM641-0.2Ca-xAl, x = 0, 0.5, 1, 2 wt.%; hereafter, all compositions are in weight percent unless stated otherwise) alloys have α-Mg, Mg2Sn, Mg7Zn3, MgZn, α-Mn, CaMgSn, AlMn, Mg32(Al,Zn)49 phases. The grain is also refined when the Al element is added, and the angular-block AlMn phases are formed in the alloys. For the ZTM641-0.2Ca-xAl alloy, the higher Al content is beneficial to elongation, and the double-aged ZTM641-0.2Ca-2Al alloy has the highest elongation, which is 13.2%. The higher Al content enhances the high-temperature strength for the as-extruded ZTM641-0.2Ca alloy; overall, the as-extruded ZTM641-0.2Ca-2Al alloy has the best performance; that is, the tensile strength and yield strength of the ZTM641-0.2Ca-2Al alloy are 159 MPa and 132 MPa at 150 °C, and 103 MPa and 90 MPa at 200 °C, respectively. [ABSTRACT FROM AUTHOR]

In this paper, Cu-6 wt%Ag alloy sheets were prepared using vacuum induction melting, heat treatment, and cold working rolling. We investigated the influence of the aging cooling rate on the microstructure and properties of Cu-6 wt%Ag alloy sheets. By reducing the cooling rate of the aging treatment, the mechanical properties of the cold-rolled Cu-6 wt%Ag alloy sheets were improved. The cold-rolled Cu-6 wt%Ag alloy sheet achieves a tensile strength of 1003 MPa and an electrical conductivity of 75% IACS (International Annealing Copper Standard), which is superior to the alloy fabricated with other methods. SEM characterization shows that the change in properties of the Cu-6 wt%Ag alloy sheets with the same deformation is due to a precipitation of the nano-Ag phase. The high-performance Cu-Ag sheets are expected to be used as Bitter disks for water-cooled high-field magnets. [ABSTRACT FROM AUTHOR]